Fire extinguisher



March 13, 1962 c. o. VAUGHN FIRE EXTINGUISHER Filed May 12, 1959 INVI JNTOR. ($421155 0. mu /aw H/g AZ'TOR/VEYS United States Patent Ofifice 3,024,847 Patented Mar. 13, I962 3,d24,847 EXTHNGUISHER Charles 0. Vaughn, Dayton, Tenn, assignor to Suburban Appliance Company, Dayton, Tenn, a corporation of Tennessee Filed May 12, 1959, Ser. No. 812,741 6 Claims. (Cl. 169-41) This invention relates to fire extinguishers and particularly to those in which the fire extinguishing agent is a dry powder which is expelled from the extinguisher by the action of a propellant gas confined in the extinguisher.

The powder employed as the fire extinguishing agent is sodium bicarbonate, or has a sodium bicarbonate base with modifying agents, as this material is a free-flowing powder. However, the composition of the fire extinguishing powder is not a part of the present invention.

One of the difficulties heretofore experienced with gaspropelled dry powder fire extinguishers has been that the contents of the extinguisher were too quickly discharged after the opening of the discharge outlet, and one of the objects of the present invention is to prolong the discharge of the powder and thus increase the efiectiveness of the extinguisher in controlling a fire.

Another disadvantage of the usual fire extinguisher of this type is that the pressure of the propellant gas falls rapidly at the opening of the discharge outlet, so that the range of the delivery of the fire extinguishing powder, while adequate at first, soon commences to shorten to an undesirable extent. It is another object of the present invention to alleviate this ditficulty.

In fire extinguishers of this type the amount of fire extinguishing powder is necessarily limited and it is important, therefore to expel as nearly all of the powder as possible. To accomplish this is an additional object of the preesnt invention.

Gas-propelled dry powder fire extinguishers as now in use are, generally speaking, constructed in such a manner as to be rechargeable after use, and for this reason are constructed of expensive materials to facilitate the recharging operation. A further important object of the present invention is to provide a gas-propelled dry powder fire xtinguisher which is intended to be used only once, and because of its throw-away or discardable character is constructed in such a way that it can be manufactured at minimum cost.

With these objectives in view my improved gas-propelled powder fire extinguisher has a container which is made of a short length of drawn seamless steel tubing of moderate thickness and has hemispherical end portions welded thereto. In the hemispherical head portion a nozzle of the break-off type and, advantageously, made merely by flattening the end portion of the eduction tube, is mounted in an opening at the top of the head portion.

A channel-shaped member is curved to fit the outer surface of the hemispherical head of the extinguisher and is secured thereto over the nozzle and is extended at the sides somewhat beyond the end of the break-off portion of the nozzle to protect it. An extension of this member downwardly from its opposite end and off-set outwardly in spaced relation to the side extinguisher container forms the handle by which the extinguisher is manipulated.

Inside of the head portion of the extinguisher the eduction tube is formed into a comparatively large coil and the opposite end of this coil is then bent downwardly and extends to the bottom of the container. this tube, which is advantageously made of copper, or other similarly flexible resilient material, renders the lower end of the tube vibratable laterally, and the mixture of powder and propellant gas, with which the extinguisher is charged, entering the lower end of the tube intermit- The coil in tently, causes the tube to vibrate and this vibration tends to agitate the powder in the proximity of the lower end of the tube. This assists in causing a maximum amount of the powder to be expelled when the discharge outlet is opened. To aid in the entry of the powder into the tube the lower end of the eduction tube is provided with an outwardly flared entrance portion or hell of considerable size, advantageously about three times the diameter of the tube.

In order to prolong the time of discharge of the powder from the extinguisher, an auxiliary chamber is associated with the extinguisher container, and is advantageously mounted within the container and adjacent but spaced somewhat from the side wall thereof. A piece of steel tubing very much smaller in diameter than the container and extending some two-thirds of the length of the container may form the auxiliary chamber. The volumetric capacity of this auxiliary chamber is much less than the volume of the container, having a volume of the order of only about one-tenth that of the container.

Such auxiliary chamber when formed by a piece of tubing has its upper end closed, and its lower end closed except for the insertion of a short piece of small tubing used in charging the extinguisher. The only communication between the auxiliary chamber and the container is a small orifice forming a greatly restricted passageway between the two.

The container is filled to the desired height with the fire extinguisher powder and the extinguisher is then charged with a propellant gas such as nitrogen, N. The gas is introduced through the small tube connected to the auxiliary chamber and thence flows through the orifice into the container and fills both to the same pressure, a pressure of two'hundred pounds per square inch being suitable.

When the discharge outlet of the extinguisher is opened the propellant gas within the container immediately commences to force the powder up the eduction tube and out of the discharge nozzle. The accompanying reduction of pressure in the container creates a pressure difference between the *gas in the auxiliary chamber and in the container, and the gas commences to flow through the small orifice mentioned. The small size of this orifice permits the gradual discharge of the gas from the auxiliary chamber into the main chamber or container and thereby prolongs the time of discharge of the powder through the eduction tube and nozzle.

The jet of gas issuing from the orifice impinges on the interior surface of the wall of the container, flowing around the sides of the cylindrical and hemispherical bottom, and converges towards the inlet to the eduction tube. During this travel it serves to stir up and agitate the powder remaining at the bottom of the container. By the combined action of such agitation and the vibratory movement of the eduction tube above referred to, I have found that only a negligible amount of powder remains after the discharging action has terminated.

The invention will be further understood from a consideration of the accompanying drawing: and the description thereof in reference thereto. It will be understood, however, that the scope of the invention is set forth in the appended claims. In these drawings:

FIG. 1 shows the extinguisher in vertical central section;

FIG. 2 is a sectional detail taken on line 22 of FIG. 1 drawn to a larger scale, and

FIG. 3 is a perspective view of the combined handle and guard member.

Referring now to these figures the fire extinguisher container is indicated by reference numeral 10 and the auxiliary chamber by reference numeral 11. The main body 12 of container 10 is cylindrical and formed of a length of drawn seamless steel tubing. Secured to the upper end of body 12 there is a substantially hemispherical head or portion 13 the lower cylindrical margin of which is telescoped into the tubing forming body 12 and welded thereto in any suitable manner as indicated, for example, at 14.

The lower end or bottom of container is formed by a similar hemispherical member 15. Member 15 is disposed a substantial distance from the bottom of the cylindrical tube forming body 12 thus leaving a skirt portion 16 which is open at the bottom and which serves to support the fire extinguisher in upright position and to protect the gas filling tube to be described. The hemispherical bottom 15 is secured in place in any suitable manner as, for example, by welding 17.

The eduction tube is indicated generally by numeral 18. At its lower end it carries a flared extrance member 19, the outer diameter of which is some three times the diameter of the eduction tube and positioned within about 4; of the surface of bottom member 15. At its upper end and Within the head member 13 the eduction tube is formed into a coil 20 which includes approximately one and onehalf turns of considerable diameter so as to impart lateral resilience to the lower portion of the tube.

The upper portion 21 of the eduction tube as it leaves coil Ztlextends through an opening in the top of head portion 13 and is fixed therein by means of welding 22, or otherwise. Just beyond this opening tube portion 21 becomes horizontal, that is, the axis of the tube is at right angles to the axis of container 10, and constitutes a nozzle having a discharge outlet 23 which is formed therein by pressing a groove 24 in the tube from both the upper and lower sides and thereby flattening the tube into the form of an elongated opening 23, as shown in FIG. 2.

Groove 24 reduces the wall thickness of the tubing to approximately one-half normal size. A further small external groove 25 is rolled into the tubing throughout the periphery of the bottom of groove 24, so as to weaken the tube at this point locally to such an extent that the outer portion 26 of the tube can be readily broken oil with the fingers. To facilitate the breaking ofl of section 26 a chain 27 with a thumb ring 28 at its end is secured at 29 to the closed and sealed outer end of projection 26.

Extending over the top of the head member 13 of the extinguisher there is a channel member 30 having flanges 31 which closely fit the surface of head member 13 and terminate in wide rectangular guard portions 32, one on each side of the break-01f extension 26 of the nozzle. Since channel member 30 is rigidly secured to the head member 13 guard members 32 give the required degree of protection to the break-off member 26. However, the web portion of the channel member 30 terminates at 33 at the end of nozzle 21 so that a space is provided between the guards 32 to provide freedom of action for the user of the extinguisher in pulling upwardly on chain 27 to break off extension 26.

The channel member 30 is provided with two L-shaped foot members 34 which are struck out of the web of the channel member and suitably welded to the surface of head member 13. Flanges 31 may also be welded in place to give added security if desired.

At its right-end channel member 30 is bent outwardly in a curve 35 and then continued straight downwardly in a handle portion 36. In order to permit such outward curving the side flanges 31 are considerably reduced in width, as shown in FIG. 1. This also makes a more acceptable handle.

The auxiliary chamber .11 comprises a section of steel tubing of appropriate diameter and length closed and sealed as indicated at 37 at its upper end closed and sealed at its lower end at 38 to the outer surface of a small copper filling tube 39. This tube extends through an aperture in the hemispherical bottom 15 and it is securely welded therein as indicated at 40. The auxiliary chamber 11 is held in place primarily by the fire extinguishing powder within container 10 and secondarily by the welding 40. The tube forming auxiliary chamber 11 is mounted with its outside surface spaced about one-half inch from the side wall of container 10, and an orifice 41 is formed in this tube and directed against the inner wall of container 10 in proximity to the greatest diameter of the hemispherical bottom member 15. The diameter of orifice 11 is about the size of a No. 70 drill or, in other words, of the order of .028.

The extinguisher container 10 is charged with the fire extinguisher powder through a small aperture 42 over which a cover plate 43 is welded after filling. After filling with powder, an appropriate gas, advantageously nitrogen, is charged through the copper tube 39, the gas flowing into the interior of container 111 through orifice 41. Because of the existence of this orifice the pressures within the auxiliary chamber 1 1 and the container 10 will be equalized. The break-off tip 26 is not sealed at its end and the chain applied until after charging so as to leave an exit for the air within the extinguisher. The charging pressure is advantageously of the order of 200 lbs. per square inch and after charging the end of tube 39 is cut off and sealed at 44 by soldering or otherwise.

The present fire extinguisher is some 4 /2 in diameter and stands approximately 1 ft. high. It contains about six pounds of fire extinguishing powder and about two and one-half ounces of compressed nitrogen. It will be understood, however, that these figures may be varied as desired and as found practicable. The steel tube forming the auxiliary chamber is about three-quarters of an inch outside diameter and about six and one-half inches long. As mentioned previously its volumetric capacity is of the order of one-tenth of the fire extinguisher container, but this ratio may be varied depending upon the extent of the prolongation of the discharge time desired.

I claim:

1. A one-use gas-propelled dry powder fire extinguisher comprising the combination of a sealed metallic container having a normally closed discharge nozzle projecting through the top thereof, a charge of dry fire extinguishing powder being confined in the container, an eduction tube disposed within the container and extending from near the bottom thereof to the nozzle, an auxiliary chamber disposed within the container having an orifice in the wall thereof near the bottom of the container, the interior of the container and of the auxiliary chamber therein being in continuous communication with each other through said orifice, said auxiliary chamber having a tube for charging the fire extinguisher with gas extending through a wall of the container, the auxiliary chamber and container being charged through said tube with gas in quantity and at a pressure effectively to expel the dry powder from the container when the discharge outlet is opened, the said orifice being of a size to permit the gradual discharge of the gas from the auxiliary chamber into the container thereby to prolong the time of discharge of the powder therefrom.

2. A one-use gas-propelled dry powder fire extinguisher as set forth in claim 1 wherein the auxiliary chamber is provided with a charging tube at its lower end which extends through and is sealed in an aperture in the bottom of the container, said auxiliary chamber being supported within the container in part by said charging tube and in part by the dry powder charge.

3. A gas-propelled dry powder fire extinguisher as set forth in claim 1, wherein the bottom portion of the container is of hemispherical shape, the entrance to the eduction tube being centrally disposed close to the surface thereof, the auxiliary chamber being disposed within and at one side of said container, and the said orifice being arranged in the outer wall of said chamber and directed against the inner wall of the container at a point located in proximity to the top of said hemispherical bottom portion, the jet of propellant gas issuing from said orifice tending to agitate the dry powder in the vicinity of the entrance to the eduction tube so as to facilitate the discharge of the powder from the container.

4. In a gas-propelled dry powder fire extinguisher, the combination of a container having a normally closed discharge outlet, an eduction tube extending from near the bottom of the container to said outlet and fixed at its upper end to the container, a quantity of dry fire extinguishing powder confined in the container, and a gas confined in said container in a quantity and at a pressure to efiectively expel the dry powder from the container When the discharge outlet is opened, said eduction tube being formed into a flexible resilient coil at its upper portion to render the entrance end of said tube laterally vibratable in response to intermittent entry of the propellant gas and powder, the vibration thereof serving to agitate the powder and assist its discharge from the container.

5. A gas-propelled dry powder fire extinguisher comprising the combination of a container having a normally closed discharge outlet, an eduction tube extending from near the container bottom to said outlet and fixed at its upper end to the container, an auxiliary chamber disposed within and at one side of said container, said chamber having a wall with an orifice therethrough disposed in the lower portion thereof and near the bottom of the container, the interiors of said container and auxiliary chamber being in communication with one another through said orifice, a quantity of dry fire extinguishing powder confined in the container, and a gas confined at the same pressure both in the container and said auxiliary chamber in a quantity and at a pressure to effectively expel the dry powder from the container when the discharge outlet is opened, said orifice permitting the gradual discharge of the gas from the auxiliary chamber into said container thereby to prolong the time of discharge of the powder therefrom, and said eduction tube being 6 formed into a coil at its upper portion to render the entrance end of said tube laterally vibratable in response to intermittent entry of the propellant gas and powder, said vibration serving to agitate the powder in proximity to said entrance and assist its discharge from the container.

6. A gas-propelled dry powder fire extinguisher as set forth in claim 5 wherein said container has a hemispherical bottom portion, the said orifice being arranged in the wall of said chamber adjacent the inner wall of the container and directed against said inner wall of the container at a point located in proximity to the top of said hemispherical bottom portion so that the jet of propellant gas issuing from said orifice strikes the surface of the container wall and thereafter tends to agitate the dry powder in proximity to the entrance to the eduction tube thereby facilitating the discharge of the powder from the container.

References Cited in the file of this patent UNITED STATES PATENTS 930,123 Banning Aug. 3, 1909 1,106,327 Areson Aug. 4, 1914 1,945,457 Warr et a1 Jan. 30, 1934 1,987,785 Meigs Ian. 15, 1935 2,268,964 Saflell Jan. 6, 1942 2,408,058 Gallagher Sept. 24, 1946 2,541,554 Smith Feb. 13, 1951 2,560,468 Morton July 10, 1951 2,580,419 Griggs Jan. 1, 1952 2,785,760 Fleming et al. Mar. 19, 1957 2,819,764 Anthony Jan. 14, 1958 FOREIGN PATENTS 236,072 Great Britain July 2, 1925 

